The current advice for historic vehicles exempt MoT status, states that you do not need to get an MoT if no ‘substantial changes’ have been made to the vehicle in the past 30 years. For example replacing the chassis, body, axles or engine to change the way the vehicle works. A ‘substantial change’ is something that means the technical characteristics of the main components have changed. When it comes to the engine, alternative cubic capacities of the same basic engine and alternative original equipment engines do not count as a substantial change.